Semiconductor structure and method for manufacturing the same

ABSTRACT

The present disclosure provides a method for manufacturing a semiconductor structure. The method includes (1) providing a substrate, (2) depositing a first electrode layer over the substrate, (3) depositing a magnetic tunneling junction (MTJ) layer on the first electrode layer, (4) depositing a second electrode layer on the MTJ layer, (5) patterning the first electrode layer, the MTJ layer and the second electrode layer to form a first electrode, an MTJ and a second electrode, (6) forming a first dielectric layer over the first electrode, the MTJ, and the second electrode, (7) removing a portion of the first dielectric layer, (8) forming a second dielectric layer over the first electrode, the MTJ, the second electrode, and an unremoved portion of the first dielectric layer. A semiconductor structure is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of prior-filed provisionalapplication No. 62/587,898, filed on Nov. 17, 2017.

BACKGROUND

Semiconductors are used in integrated circuits for electronicapplications, including radios, televisions, cell phones, and personalcomputing devices. One type of well-known semiconductor device is thesemiconductor storage device, such as dynamic random access memories(DRAMs), or flash memories, both of which use charges to storeinformation.

A more recent development in semiconductor memory devices involves spinelectronics, which combines semiconductor technology and magneticmaterials and devices. The spin polarization of electrons, rather thanthe charge of the electrons, is used to indicate the state of “1” or“0.” One such spin electronic device is a spin torque transfer (STT)magnetic tunneling junction (MTJ) device. MTJ device includes freelayer, tunnel layer, and pinned layer. The magnetization direction offree layer can be reversed by applying a current through tunnel layer,which causes the injected polarized electrons within free layer to exertso-called spin torques on the magnetization of free layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a flowchart illustrating a method of manufacturing asemiconductor structure according to some embodiments of presentdisclosure.

FIG. 2 to FIG. 12 are cross sections of a semiconductor structurefabricated at various stages, in accordance with some embodiments of thepresent disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “beneath,”“below,” “lower,” “above,” “upper,” and the like, may be used herein forease of description to describe one element or feature's relationship toanother element(s) or feature(s) as illustrated in the figures. Thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. The apparatus may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein may likewise be interpretedaccordingly.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in therespective testing measurements. Also, as used herein, the term “about”generally means within 10%, 5%, 1%, or 0.5% of a given value or range.Alternatively, the term “about” means within an acceptable standarderror of the mean when considered by one of ordinary skill in the art.Other than in the operating/working examples, or unless otherwiseexpressly specified, all of the numerical ranges, amounts, values andpercentages such as those for quantities of materials, durations oftimes, temperatures, operating conditions, ratios of amounts, and thelikes thereof disclosed herein should be understood as modified in allinstances by the term “about.” Accordingly, unless indicated to thecontrary, the numerical parameters set forth in the present disclosureand attached claims are approximations that can vary as desired. At thevery least, each numerical parameter should at least be construed inlight of the number of reported significant digits and by applyingordinary rounding techniques. Ranges can be expressed herein as from oneendpoint to another endpoint or between two endpoints. All rangesdisclosed herein are inclusive of the endpoints, unless specifiedotherwise.

Embedded magnetoresistive random access memory (MRAM) cell in acomplementary metal-oxide-semiconductor (CMOS) structure has beencontinuously developed. A semiconductor memory device with embedded MRAMcells includes an MRAM cell region and a logic region. The MRAM cellregion may comprise a plurality of MRAM cells. The logic region maycomprise a plurality of conductive lines or metal lines. The pluralityof conductive lines may provide routing for the plurality of MRAM cells.The logic region and the MRAM cell region may be disposed in differentregions in the semiconductor memory device. For example, the MRAM cellregion may be located at the center of the semiconductor memory devicewhile the logic region may be located at a periphery of thesemiconductor memory device. However, such an example is not intended tobe limiting. Other arrangements of the MRAM cell region and the logicregion fall within the contemplated scope of the present disclosure.

In the MRAM cell region, a transistor structure may be disposed under anMRAM structure. In some embodiments, an MRAM cell is embedded in ametallization layer prepared in a back-end-of-line (BEOL) operation. Insome embodiments, transistor structures in the MRAM cell region and thelogic region are disposed in a same semiconductor substrate and preparedin a front-end-of-line (FEOL) operation, and thus are substantiallyidentical. The MRAM cell can be embedded in any position of themetallization layer, for example, between adjacent metal line layersextending in parallel over the semiconductor substrate. In someembodiments, the embedded MRAM cell can be located between a 4^(th)metal line layer and a 5^(th) metal line layer in the MRAM cell region.In the logic region, the 4^(th) metal line layer is connected to the 5thmetal line layer though a 4^(th) metal via, which is located between the4^(th) metal line layer and the 5^(th) metal line layer. In other words,taking the MRAM cell region and the logic region into consideration, anembedded MRAM cell has a thickness of at least a portion of the 5^(th)metal line layer and the 4^(th) metal via. The architecture of the metalline layers herein is exemplary and not limiting. In general, peoplehaving ordinary skill in the art can understand that the MRAM cell islocated between an N^(th) metal line layer and an (N+1)^(th) metal linelayer, where N is an integer greater than or equal to 1.

The embedded MRAM cell includes a magnetoresitive cell. In someembodiments, the magnetoresitive cell is a magnetic tunneling junction(MTJ) composed of ferromagnetic materials. The MTJ may comprise aferromagnetic free layer, a tunnel layer, and a ferromagnetic fixedlayer. The ferromagnetic free layer and the ferromagnetic fixed layerare electrically coupled to the MTJ for signal/bias conveyance.Following the example previously provided, the ferromagnetic free layeris further connected to the N^(th) metal line layer, whereas theferromagnetic fixed layer is further connected to the (N+1)^(th) metalline layer.

The magnetization direction of the ferromagnetic free layer can bereversed by applying a current through the tunnel layer, which causesinjected polarized electrons within the ferromagnetic free layer toexert spin torques on the magnetization of the ferromagnetic free layer.The ferromagnetic fixed layer has a fixed magnetization direction. Whencurrent flows in the direction from the ferromagnetic free layer to theferromagnetic fixed layer, electrons flow in a reverse direction, thatis, from the ferromagnetic fixed layer to the ferromagnetic free layer.The electrons are polarized to the same magnetization direction of theferromagnetic fixed layer after passing the ferromagnetic fixed layer,flow through the tunnel layer and then into and accumulate in theferromagnetic free layer. Eventually, the magnetization of theferromagnetic free layer is parallel to that of the ferromagnetic fixedlayer, and the MTJ device will be at a low resistance state. Suchelectron injection caused by current is referred to as a majorinjection.

When current flowing from the ferromagnetic fixed layer to theferromagnetic free layer is applied, electrons flow in the directionfrom the ferromagnetic free layer to the ferromagnetic fixed layer.Electrons having the same polarization as the magnetization direction ofthe ferromagnetic fixed layer are able to flow through the tunnel layerand into the ferromagnetic fixed layer. Conversely, electrons withpolarization different from the magnetization of the ferromagnetic fixedlayer are reflected (blocked) by the ferromagnetic fixed layer andaccumulate in the ferromagnetic free layer. Eventually, themagnetization of the ferromagnetic free layer becomes anti-parallel tothat of the ferromagnetic fixed layer, and the MTJ device will be at ahigh resistance state. Such electron injection caused by current isreferred to as a minor injection.

In a series of manufacturing operations, an ion beam etching (IBE) maybe incorporated for the sidewall damage reduction and removal whenpatterning the MTJ structure. Compared to plasma etching, IBE providesmore physical bombardment than chemical-assisted removal and thuspreventing sidewall of the as-patterned MTJ structure from chemicaldamages. Alternatively, IBE can be exploited after plasma etching forsidewall chemical damage removal. The application of IBE in MTJpatterning effectively improves the tunneling magnetoresistance and thecoercivity of the memory device.

However, during IBE treatment, the ion beam may cause a bottom electrodeof the MTJ structure to re-sputter elements to the sidewall of the MTJstructure. Consequently, this may short the MTJ structure anddeteriorate performance of the memory device.

Referring to FIG. 1, FIG. 1 is a flowchart illustrating a method 100 ofmanufacturing a semiconductor structure according to some embodiments ofthe present disclosure. In some embodiments, the method 100 includesoperations 101-108. In operation 101, a substrate is provided. Inoperation 102, a first electrode layer of a MTJ structure is depositedover the substrate. In operation 103, an MTJ layer is deposited on thefirst electrode layer. In operation 104, a second electrode layer isdeposited over the MTJ layer. In operation 105, the first electrodelayer, the MTJ layer, and the second electrode layer are patterned toform a first electrode, an MTJ, and a second electrode. In operation106, a first dielectric layer is formed over the first electrode, theMTJ, and the second electrode. In operation 107, a portion of the firstdielectric layer is removed. In operation 108, a second dielectric layeris formed over the first electrode, the MTJ, the second electrode, andan unremoved portion of the first dielectric layer.

The method 100 is merely an example, and is not intended to limit thepresent disclosure beyond what is explicitly recited in the claims.Additional operations can be provided before, during, and after themethod 100, and some operations described can be replaced, eliminated,or moved around for additional embodiments of the method.

FIG. 2 to FIG. 12 are cross sections of a semiconductor structurefabricated at various stages, in accordance with some embodiments of thepresent disclosure. Referring to FIG. 2 and operation 101 in FIG. 1, thesubstrate 200 is provided. In some embodiments, the substrate 200 is asemiconductor substrate. In some embodiments, the substrate 200 may bebut is not limited to, for example, a silicon substrate. In someembodiment, substrate 200 is a semiconductor substrate, such as asilicon substrate, although it may include other semiconductormaterials, such as silicon germanium, silicon carbide, gallium arsenide,or the like. In some embodiments, the substrate 200 is a p-typesemiconductor substrate (P-Substrate) or an n-type semiconductorsubstrate (N-Substrate) comprising silicon. Alternatively, the substrate200 includes another elementary semiconductor, such as germanium; acompound semiconductor including silicon carbide, gallium arsenic,gallium phosphide, indium phosphide, indium arsenide, and/or indiumantimonide; an alloy semiconductor including SiGe, GaAsP, AlInAs,AlGaAs, GalnAs, GaInP, and/or GaInAsP; or combinations thereof. In yetanother alternative, the substrate 200 is a semiconductor on insulator(SOI). In other alternatives, substrate 200 may include a doped epilayer, a gradient semiconductor layer, and/or a semiconductor layeroverlying another semiconductor layer of a different type, such as asilicon layer on a silicon germanium layer. The substrate 200 may or maynot include doped regions, such as a p-well, an n-well, or combinationthereof.

In some embodiments, the substrate 200 has a transistor structure 201.The substrate 200 further includes heavily doped regions such as sources203 and drains 205 at least partially in the substrate 200. A gate 207is positioned over a top surface of the substrate 200 and between thesource 203 and the drain 205. Contact plugs 208 are formed ininter-layer dielectric (ILD) 209, and may be electrically coupled to thetransistor structure 201. In some embodiments, the ILD 209 is formed onthe substrate 200. The ILD 209 may be formed by a variety of techniquesfor forming such layers, e.g., chemical vapor deposition (CVD),low-pressure CVD (LPCVD), plasma-enhanced CVD (PECVD), sputtering andphysical vapor deposition (PVD), thermal growing, and the like. The ILD209 above the substrate 200 may be formed from a variety of dielectricmaterials and may, for example, be an oxide (e.g., Ge oxide), anoxynitride (e.g., GaP oxynitride), silicon dioxide (SiO₂), anitrogen-bearing oxide (e.g., nitrogen-bearing SiO₂), a nitrogen-dopedoxide (e.g., N₂-implanted SiO₂), silicon oxynitride (Si_(x)O_(y)N_(z)),and the like.

FIG. 2 shows a planar transistor having a doped region in the substrate200. However, the present disclosure is not limited thereto. Anynon-planar transistor, such as a FinFET structure, can have raised dopedregions.

In some embodiments, a shallow trench isolation (STI) 211 is provided todefine and electrically isolate adjacent transistors. A number of STIs211 are formed in the substrate 200. The STI 211, which may be formed ofsuitable dielectric materials, may be provided to isolate a transistorelectrically from neighboring semiconductor devices such as othertransistors. The STI 211 may, for example, include an oxide (e.g., Geoxide), an oxynitride (e.g., GaP oxynitride), silicon dioxide (SiO₂), anitrogen-bearing oxide (e.g., nitrogen-bearing SiO₂), a nitrogen-dopedoxide (e.g., N₂-implanted SiO₂), silicon oxynitride (Si_(x)O_(y)N_(z)),and the like.

In some embodiments, because MRAM cell can be embedded in any positionof the metallization layer, the omission of a portion of themetallization structure is represented by dots. In some embodiments, themetallization layer comprises the metal lines and metal vias.

In some embodiments, a barrier layer 310 in a form of a stacking layerincluding a SiC layer 311 and a tetraethyl orthosilicate (TEOS) layer312 are blanket deposited over substrate 200. In some embodiments, afirst electrode via hole 301′ is opened in the barrier layer 310.Alternatively, the TEOS 312 can be replaced or combined withsilicon-rich oxides (SRO).

In some embodiments, the barrier layer 310 may be formed by a variety oftechniques, e.g., chemical vapor deposition (CVD), low-pressure CVD(LPCVD), plasma-enhanced CVD (PECVD), sputtering and physical vapordeposition (PVD), thermal growing, and the like. In some embodiments, aphotoresist layer (not shown) is patterned over the stacking barrierlayer 310 to expose a first electrode region of the MTJ structure. Insome embodiments, the first electrode via hole 301′ may be formed in thebarrier layer 310 by a suitable dry etch operation.

Referring to FIG. 3 and operation 102 in FIG. 1, a via or a bottomelectrode via 330′ and a diffusion layer 320 are deposited over thesubstrate 200. In some embodiments, the via or the bottom electrode via330′ functions as a portion of the bottom electrode in the MRAMstruture. In some embodiments, the diffusion barrier layer 320 isconformably deposited prior to the filling of the bottom electrode via330′. In some embodiments, the bottom electrode via 330′ is formed overthe diffusion barrier layer 320.

Referring to FIG. 4, in some embodiments, the bottom electrode via 330′and the diffusion barrier layer 320 are etched back to level with a topsurface of the barrier layer 310. In some embodiments, the firstelectrode layer 330A is then formed and thinned to a predeterminedthickness. In some embodiments, the first electrode layer 330A may beformed by a variety of techniques, e.g., high-density ionized metalplasma (IMP) deposition, high-density inductively coupled plasma (ICP)deposition, sputtering, physical vapor deposition (PVD), chemical vapordeposition (CVD), low-pressure chemical vapor deposition (LPCVD),plasma-enhanced chemical vapor deposition (PECVD), and the like. In someembodiments, the first electrode layer 330A may be composed of metalnitride such as TaN, TiN, or the combinations thereof.

Referring to FIG. 5 and operation 103 in FIG. 1, the MTJ layer 340A isdeposited on the first electrode layer 330A. In some embodiments, theMTJ layer 340A is deposited over the first electrode layer 330A of thefirst electrode layer 330A. In some embodiments, the MTJ layer 340A isdeposited in a form of multiple material stacked over the firstelectrode layer 330A. The MTJ layer 340A may be formed by variety oftechniques, e.g., high-density ionized metal plasma (IMP) deposition,high-density inductively coupled plasma (ICP) deposition, sputtering,physical vapor deposition (PVD), chemical vapor deposition (CVD),low-pressure chemical vapor deposition (LPCVD), plasma-enhanced chemicalvapor deposition (PECVD), and the like.

In some embodiments, the MTJ layer 340A may include the ferromagneticlayers, the spacers, and the capping layer. The capping layer is formedon the ferromagnetic layer. Each of the ferromagnetic layers may includeferromagnetic material, which may be metal or metal alloy, for example,Fe, Co, Ni, CoFeB, FeB, CoFe, FePt, FePd, CoPt, CoPd, CoNi, TbFeCo, CrNior the like. The spacer may include non-ferromagnetic metal, forexample, Ag, Au, Cu, Ta, W, Mn, Pt, Pd, V, Cr, Nb, Mo, Tc, Ru or thelike. Another spacer may also include insulator, for example, Al₂O₃,MgO, TaO, RuO or the like. The capping layer may includenon-ferromagnetic material, which may be a metal or an insulator, forexample, Ag, Au, Cu, Ta, W, Mn, Pt, Pd, V, Cr, Nb, Mo, Tc, Ru, Ir, Re,Os, Al₂O₃, MgO, TaO, RuO or the like. The capping layer may reduce writecurrent of its associated MRAM cell. The ferromagnetic layer mayfunction as a free layer whose magnetic polarity or magnetic orientationcan be changed during write operation of its associated MRAM cell. Theferromagnetic layers and the spacer may function as a fixed or pinnedlayer whose magnetic orientation may not be changed during operation ofits associated MRAM cell. It is contemplated that the MTJ layer 340A mayinclude an antiferromagnetic layer in accordance with other embodiments.

Referring to FIG. 5 and operation 104 in FIG. 1, the second electrodelayer 350A is deposited over the MTJ layer 340A. The second electrodelayer 350A may be formed by a variety of techniques, e.g., high-densityionized metal plasma (IMP) deposition, high-density inductively coupledplasma (ICP) deposition, sputtering, physical vapor deposition (PVD),chemical vapor deposition (CVD), low-pressure chemical vapor deposition(LPCVD), plasma-enhanced chemical vapor deposition (PECVD), and thelike. In some embodiments, the second electrode layer 350A may includemetal nitrides. Materials constituting the first electrode layer 330Aand the second electrode layer 350A may or may not be identical.

Referring to FIG. 6 and operation 105 in FIG. 1, the MTJ layer, thesecond electrode layer, and the first electrode layer are patterned in alithography operation to form a first electrode 330, an MTJ 340, and asecond electrode 350 of the MTJ structure 300. In some embodiments, theMTJ structure 300 at least includes a bottom electrode, a top electrode,and an MTJ. In some embodiments, the first electrode 330 and the bottomelectrode via 330′ may collectively function as the bottom electrode ofthe MTJ structure 300. In some embodiments, the second electrode 350 mayfunction as the top electrode of the MTJ structure 300. In someembodiments, the first electrode 330, the MTJ 340, and the secondelectrode 350 are patterned in a single operation.

In some embodiments, a mask layer (not shown) exposing a desired MTJpattern is formed over the second electrode layer 350A (as shown in FIG.5) for the ensuing MTJ structure formation. The mask layer possessingthe desired MTJ pattern and may have a multi-layer structure, which mayinclude, for example, an oxide layer, an advanced patterning film (APF)layer and an oxide layer. Each of the oxide layer, the APF layer, andthe oxide layer may be formed by a variety of techniques, e.g.,high-density ionized metal plasma (IMP) deposition, high-densityinductively coupled plasma (ICP) deposition, sputtering, physical vapordeposition (PVD), chemical vapor deposition (CVD), low-pressure chemicalvapor deposition (LPCVD), plasma-enhanced chemical vapor deposition(PECVD), and the like. In some embodiments, the mask layer is configuredto pattern the MTJ 340 and the second electrode 350. For example, awidth of the masking region is determined according to the desired MTJdiameter. In some embodiments, the MTJ 340 and the second electrode 350may be formed by an RIE to have a trapezoidal shape viewing from a crosssection.

In some embodiments, the first electrode 330 is electrically coupledwith the doped region. In some embodiments, the doped region is thedrain 205 or the source 203. In other embodiments, the first electrode330 is electrically coupled with the gate 207. In some embodiments, thegate 207 may be a polysilicon gate or a metal gate.

Referring to FIG. 7 and operation 106 in FIG. 1, the first dielectriclayer 360 is formed over the first electrode 330, the MTJ 340, thesecond electrode 350, and the barrier layer 310. In some embodiments,the first dielectric layer 360 has an overall thickness of from about 1nm to about 12 nm. In some embodiments, the thickness d2 of theas-deposited first dielectric layer 360 on the sidewall 340S of the MTJ340 is thinner than the as-deposited thickness d1 on the top surface350S of and the second electrode 350. In some embodiments, theas-deposited thickness d1 may be from about 3 nm to about 12 nm. In someembodiments, the ratio (d1/d2) between the thickness d1 and thethickness d2 may be from about 1.2 to about 3. In some embodiments, aratio (d2/W) of the thickness d2 to the critical dimension W of the MTJ340 may be in a range from about 1% to about 12%. In some embodiments,the critical dimension W is measured as a width of the tunneling barrierlayer of the MTJ 340.

In some embodiments, the first dielectric layer 360 includes materialsof silicon oxide (SiO_(x)), silicon nitride (SiN_(x)), siliconoxynitride (SiON), or silicon carbide (SiC), which may be formed byplasma deposition operation, such as Atomic layer deposition (ALD),physical vapor deposition (PVD), or chemical vapor deposition (CVD)including plasma enhanced chemical vapor deposition (PECVD).

Referring to FIG. 8, FIG. 9, and operation 107 in FIG. 1, a portion ofthe first dielectric layer 360 is removed. In some embodiments, thefirst dielectric layer 360 is removed by performing a dry etch appliedfrom a tilted angle θ. In some embodiments, the dry etch in the presentoperation includes physical etching techniques such as ion beam etch(IBE). In some embodiments, the present dry etch operation can be anysuitable dielectric dry etch. In some embodiments, an incident angle θbetween the ion beam direction and a sidewall of the MTJ is between 20°and 80°. This is merely examples and is not intended to be limiting.

Referring to FIG. 9, in some embodiments, the sidewall 340S of the MTJ340 may be exposed or still partially covered by the first dielectriclayer 360 after operation 107. In some embodiments, the sidewall 340S ofthe MTJ 340 is fully exposed. By exposing the sidewall 340S of the MTJ340, defects or damages on the sidewall 340S of the MTJ 340 may beremoved at the same time.

In some embodiments, the first dielectric layer 360 may prevent thebottom electrode via 330′ and the first electrode 330 from unnecessaryetching. Furthermore, the first dielectric layer 360 may prevent there-sputtering from the top surface 330S of the bottom electrode via 330′or the first electrode 330 to the sidewall 340S of the MTJ 340.Consequently, MTJ short caused by the aforesaid re-sputtering may beavoided. On the other hand, without depositing the first dielectriclayer 360, an appropriate tilted angle θ shall be carefully chosen tomitigate the re-sputtering effect. For example, a smaller tilted angle θpossesses a greater vertical component with respect to ion beambombardment, whereas a greater tilted angle θ possesses a smallervertical component. Therefore, smaller tilted angle θ is prone togenerate severe bottom electrode re-sputtering. However, greater tiltedangle θ accompanies shadowing effect in an etching operation. With thedeposition of the first dielectric layer 360 in the present disclosure,the tilted angle θ of the dry etch operation may be chosen in a wideroperation window.

In some embodiments, a portion of the first dielectric layer 360 over atop surface 330S of the bottom electrode via 330′ and over a top surface350S of the second electrode 350 may not be removed after operation 107.In some embodiments, the portion of the first dielectric layer 360 overthe top surface 350S of the second electrode 350 comprises a remainingthickness of from about 1 nm to about 5 nm. In some embodiments, theportion of the first dielectric layer 360 over the top surface 330S ofthe bottom electrode via 330′ comprises a remaining thickness of fromabout 1 nm to about 8 nm. In some embodiments, the portion of the firstdielectric layer 360 over the top surface 350S of the second electrode350 is thinner than the portion of the first dielectric layer 360 overthe top surface 330S of the bottom electrode via 330′. Alternatively,the portion of the first dielectric layer 360 over the top surface 350Sof the second electrode 350 may be removed.

In some embodiments, the differences between the as-depositedthicknesses d1 and d2 (as shown in FIG. 7) of the first dielectric layer360 are designed based on the ion beam etching rates with respect to thefirst dielectric layer 360 at the sidewall 340S and the top surface 350Sof the second electrode 350. It is desirable that the first dielectriclayer 360 at top surface 350S retains a certain thickness while thefirst dielectric layer 360 at the sidewall 340S of the MTJ 340 iscompletely etched. In some embodiments, the thickness of the firstdielectric layer 360 at the top surface of the bottom electrode via 330′and the barrier layer 310 is similar to that at the top surface 350S(collectively “horizontal portion”). The thickness at the horizontalportion of the first dielectric layer 360 shall be thick enough toprevent bottom electrode from exposure during etching operation andcausing re-sputtering of the conductive materials to the sidewall 340Sof the MTJ 340.

Referring to FIG. 10 and operation 108 in FIG. 1, the second dielectriclayer 370 is formed over the first electrode 330, the MTJ 340, thesecond electrode 350, the barrier layer 310, and an unremoved portion ofthe first dielectric layer 360. In some embodiments, the seconddielectric layer 370 is a protection layer such as a nitride layer. Insome embodiments, the second dielectric layer 370 includes materials ofsilicon oxide (SiO_(x)), silicon nitride (SiN_(x)), silicon oxynitride(SiON), or silicon carbide (SiC), which may be formed by plasmadeposition operation, such as Atomic layer deposition (ALD), physicalvapor deposition (PVD), or chemical vapor deposition (CVD) includingplasma enhanced chemical vapor deposition (PECVD). In some embodiments,the second dielectric layer 370 and the first dielectric layer 360 mayinclude same or different materials.

In some embodiments, the as-deposited second dielectric layer 370 has anoverall thickness of from about 1 nm to about 50 nm. In someembodiments, the thickness F2 of the as-deposited second dielectriclayer 370 on the sidewall of the MTJ 340 is thinner than theas-deposited thickness F1 on the top surface of the second electrode350. In some embodiments, the as-deposited thickness F1 may be fromabout 10 nm to about 50 nm. In some embodiments, the ratio (F1/F2) maybe in a range from about 1.2 to about 3.5. This is merely examples andis not intended to be limiting. In some embodiments, the sidewall 340Sof the MTJ 340 is in direct contact with the second dielectric layer 370because the portion of the first dielectric layer 360 at the sidewall340S has been substantially removed during the dry etch operationpreviously discussed in FIG. 8. Depositing the second dielectric layer370 over the sidewall 340S also prevents oxidation or othercontamination at the sidewall 340S. In some embodiments, the sidewall ofthe second electrode 350 is also in direct contact with the seconddielectric layer 370.

Referring to FIG. 11, in some embodiment, the top surface 350S of thesecond electrode 350 is exposed from the first dielectric layer 360 andthe second dielectric layer 370. In some embodiment, an etch-backoperation is performed on the first dielectric layer 360 and the seconddielectric layer 370 such that the top surface 350S of the secondelectrode 350 is exposed from the first dielectric layer 360 and thesecond dielectric layer 370.

Referring to FIG. 12, in some embodiment, a third dielectric layer 380is formed over the second dielectric layer 370, and a planarizationoperation is taken place after the formation of the third dielectriclayer 380. In some embodiments, the third dielectric layer 380 such as aTEOS layer is deposited over the second dielectric layer 370. In someembodiments, a thickness of the third dielectric layer 380 is to bedetermined according to a level of a top surface thereof relative to thetop surface of the second electrode 350.

In some embodiments, subsequent operation may further include formingvarious layers, such as subsequent barrier layers 391, 392 are formed.In some embodiment, a low k dielectric layer 393 is formed over thebarrier layer 391, 392, and a via hole is formed to penetrate the low kdielectric layer 393 and the barrier layer 391, 392 underneath, exposingthe top surface of the second electrode 350. In some embodiments, thevia hole is filled with conductive materials as previously described toform metal via 394 as a part of metallization or interconnect structure.

Subsequent operations may further include forming variouscontacts/vias/lines and multi-layer interconnect features (e.g., metallayers and interlayer dielectrics) over the substrate, configured toconnect the various features or structures of the integrated circuitdevice. The additional features may provide electrical interconnectionto the device including the formed metal gate structures. For example, amultilayer interconnection includes vertical interconnects, such asconventional vias or contacts, and horizontal interconnects, such asmetal lines. The various interconnection features may implement variousconductive materials including copper, tungsten, and/or silicide. In oneexample a damascene and/or dual damascene operation is used to form acopper related multilayer interconnection structure.

In some embodiments, the first dielectric layer may prevent the bottomelectrode via and the first electrode from unnecessary etching andre-sputtering. Further, the first dielectric layer may prevent there-sputtering from the top surface of the bottom electrode via or thefirst electrode to the sidewall of the MTJ. Consequently, the MTJ shortissue caused by the re-sputtering from the first electrode or the bottomelectrode via may be avoided. Moreover, conventionally, the largerincident angle θ may be chose because of the smaller angle may causemore re-sputtering from the top surface of the bottom electrode via orthe first electrode. In some embodiments, with the first dielectriclayer preventing the re-sputtering from the bottom electrode via or thefirst electrode, the incident angle θ of the dry etch may be chose moreflexibly.

Referring to FIG. 12, the semiconductor structure 1 includes a via 330′,a first electrode 330 on the via 330′, a magnetic tunneling junction(MTJ) 340 over the first electrode 330, a second electrode 350 over theMTJ 340, a first dielectric layer 360 on a top surface of the via 330′,a second dielectric layer 370 over the first electrode 330, the MTJ 340,the second electrode 350, and the first dielectric layer 360. A sidewallof the MTJ 340 is in contact with the second dielectric layer 370. Thesemiconductor structure 1 serves only as one example.

Some embodiments of the present disclosure provide a method formanufacturing a semiconductor structure. The method includes (1)providing a substrate, (2) depositing a first electrode layer over thesubstrate, (3) depositing a magnetic tunneling junction (MTJ) layer onthe first electrode, (4) depositing a second electrode layer on the MTJlayer, (5) patterning the first electrode layer, the MTJ layer, and thesecond electrode layer to form a first electrode, an MTJ, and a secondelectrode, (6) forming a first dielectric layer over the firstelectrode, the MTJ, and the second electrode, (7) removing a portion ofthe first dielectric layer, (8) forming a second dielectric layer overthe first electrode, the MTJ, the second electrode, and an unremovedportion of the first dielectric layer.

Some embodiments of the present disclosure provide a semiconductorstructure, including a first electrode via, a first electrode on thefirst electrode via, a magnetic tunneling junction (MTJ) over the firstelectrode, a second electrode over the MTJ, a first dielectric layer ona top surface of the first electrode via, a second dielectric layer overthe first electrode, the MTJ, the second electrode, and the firstdielectric layer. A sidewall of the MTJ is in contact with the seconddielectric layer.

Some embodiments of the present disclosure provide a method formanufacturing a semiconductor structure. The method includes (1) forminga magnetic tunneling junction (MTJ) structure over a substrate, (2)forming a first dielectric layer over the MTJ structure, (3) removing aportion of the first dielectric layer thereby exposing a sidewall of theMTJ structure, (4) forming a second dielectric layer over the MTJstructure and the first dielectric layer.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and operationsdescribed in the specification. As one of ordinary skill in the art willreadily appreciate from the disclosure of the present processes,machines, manufacture, compositions of matter, means, methods, oroperations, presently existing or later to be developed, that performsubstantially the same function or achieve substantially the same resultas the corresponding embodiments described herein may be utilizedaccording to the present disclosure. Accordingly, the appended claimsare intended to include within their scope such processes, machines,manufacture, compositions of matter, means, methods, or operations.

What is claimed is:
 1. A method for manufacturing a semiconductorstructure, the method comprising: providing a substrate; depositing afirst electrode layer over the substrate; depositing a magnetictunneling junction (MTJ) layer on the first electrode layer; depositinga second electrode layer on the MTJ layer; patterning the firstelectrode layer, the MTJ layer, and the second electrode layer to form afirst electrode, an MTJ and a second electrode; forming a firstdielectric layer over the first electrode, the MTJ, and the secondelectrode; removing a portion of the first dielectric layer; and forminga second dielectric layer over the first electrode, the MTJ, the secondelectrode, and an unremoved portion of the first dielectric layer,wherein prior to the removing the portion of the first dielectric layer,the first dielectric layer at a sidewall of the MTJ is thinner than thefirst dielectric layer at a top surface of the second electrode.
 2. Themethod of claim 1, wherein the removing the portion of the firstdielectric layer comprises exposing a sidewall of the MTJ.
 3. The methodof claim 1, further comprising: forming a first electrode via prior tothe depositing the first electrode layer, wherein the removing theportion of the first dielectric layer comprises leaving remainingportion of the first dielectric layer over a top surface of the firstelectrode via and over a top surface of the second electrode.
 4. Themethod of claim 3, wherein the remaining portion of the first dielectriclayer over the top surface of the second electrode comprises a thicknessof from about 1 nm to about 5 nm.
 5. The method of claim 3, wherein theremaining portion of the first dielectric layer over the top surface ofthe first electrode via comprises a thickness of from about 1 nm toabout 8 nm.
 6. The method of claim 3, wherein prior to the removing thefirst dielectric layer, the ratio between a thickness of the firstdielectric layer on the top surface of the second electrode and athickness of the first dielectric layer on a sidewall of the MTJ is in arange from about 1.2 to about
 3. 7. The method of claim 1, wherein theforming the first dielectric layer comprises depositing the firstdielectric layer having a thickness of from 1 nm to about 12 nm.
 8. Themethod of claim 1, wherein the removing the portion of the firstdielectric layer comprises performing an angled dry etch.
 9. The methodof claim 1, wherein prior to the removing the first dielectric layer, aratio of a thickness of the first dielectric layer on a sidewall of theMTJ to a critical dimension of the MTJ is in a range from about 1% toabout 12%.
 10. A method for manufacturing a semiconductor structure, themethod comprising: forming a magnetic tunneling junction (MTJ) structureover a substrate; forming a first dielectric layer over the MTJstructure; removing a portion of the first dielectric layer therebyexposing a sidewall of the MTJ structure; and forming a seconddielectric layer over the MTJ structure and an unremoved portion of thefirst dielectric layer, wherein prior to the removing of the portion ofthe first dielectric layer, the first dielectric layer at a sidewall ofthe MTJ structure is thinner than the first dielectric layer at a topsurface of the MTJ structure.
 11. The method of claim 10, wherein theforming the first dielectric layer comprises depositing the firstdielectric layer having a thickness of from 1 nm to about 12 nm.
 12. Themethod of claim 10, wherein the removing the portion of the firstdielectric layer comprises performing an angled dry etch.
 13. The methodof claim 10, wherein prior to the removing the first dielectric layer, aratio of a thickness of the first dielectric layer on the sidewall ofthe MTJ structure to a critical dimension of the MTJ structure is in arange from about 1% to about 12%.
 14. The method of claim 10, whereinprior to the removing the first dielectric layer, a ratio of a thicknessof the first dielectric layer on a top surface of the MTJ structure to athickness of the first dielectric layer on the sidewall of the MTJstructure is in a range from about 1.2 to about
 3. 15. A method formanufacturing a semiconductor structure, the method comprising: forminga magnetic tunneling junction (MTJ) structure over a substrate; forminga first dielectric layer over the MTJ structure; performing an ion beametching thereby removing a portion of the first dielectric layer;forming a second dielectric layer over a remaining portion of the firstdielectric layer and along sidewalls of the MTJ structure; forming athird dielectric layer over a portion of the second dielectric layersuch that the third dielectric layer has a top surface leveled to a topsurface of the second dielectric layer, wherein performing the ion beametching comprises exposing a sidewall of the MTJ structure.
 16. Themethod of claim 15, further comprising an etch back operation afterforming the second dielectric layer over the MTJ structure and the firstdielectric layer to expose a top surface of the MTJ structure.
 17. Themethod of claim 15 wherein the remaining portion of the first dielectriclayer is on a top surface of the MTJ structure.
 18. The method of claim15, wherein performing the ion beam etching comprises performing anangled dry etch.
 19. The method of claim 15, wherein the firstdielectric layer at a sidewall of the MTJ structure is thinner than thefirst dielectric layer at a top surface of the MTJ structure.